Quality Textiles International is an organization that weaves fabric and then prepares the required sheet lengths as desired by customers. They have received recent complaints that the fabric weight, measured in ounces per square inch, is not meeting customer requirements, which are very close to the control limits. Quality Textiles International’s quality assurance department checks the fabric weight on regular basis and knows that their process for fabric weight has a mean of 2.73 oz/in2 and a standard deviation of 0.31.
The following table shows 50 fabric weight measurements of fabric samples collected by the quality assurance department:
Observation Fabric weight
1 2.78
2 2.46
3 3.00
4 2.80
Not enough room for all of it. Use the histogram to determine how many points are out of control according to the upper control limit and lower control limit.
Based on your data analysis, what assumptions and recommendations would you make for getting at root cause and improving the manufacturing process?